The present invention relates to an ink jet recording apparatus which records information on a recording medium with ink, a method of controlling the apparatus, and a method of replenishing ink stored in a main tank to a subtank for temporarily storing the replenished ink.
Further, the present invention relates to an ink supply system incorporated in the apparatus, and a method of managing the supplying ink amount executed by the ink supply system.
Recently, a digital camera provided with a CCD (charge coupled device) and a memory device has spread in place of a camera using a silver halide film. A picture taken by such a digital camera is recorded on a recording medium by a recording apparatus. As this recording apparatus, for example, an ink jet printer is used, and as a recording medium, for example, print paper is used. Under the circumstances, also in a laboratory where the silver halide film is developed and an image is printed on photographic paper thereby to make a photograph, an ink jet printer has been installed in order to print a digital image.
In this ink jet printer, a recording head, which pressurizes ink supplied from an ink tank and ejects an ink droplet, is reciprocated in the width direction of paper thereby to perform printing. The ink jet printer which can perform a large amount of printing by such the system includes a main ink tank having large volume (hereinafter referred to as a main tank) for each color, and a sub-ink tank (hereinafter referred to as a subtank) having small volume for each color, which is connected to each main tank by a tube. The subtank is airtightly formed of a flexible material having flexibility in the shape of a bag so as to be variable in volume.
As a method of increasing the number of prints per time in such a laboratory, it is considered that plural ink jet printers are operated. However, since many main tanks (multiplying the number of ink jet printers by the number of colors) are required, there is a problem on replacement of the main tanks.
In a case where ink is supplied from a single main tank for each color to print heads for each color of the plural ink jet printers, the number of the main tanks requires only the number of colors. However, in a case where the amount of ink ejection in the recording head is large, dynamic pressure in an ink supply passage becomes large, so that the ink supply runs short and printing quality lowers.
Further, since the dynamic pressure is produced due to the difference in length of the ink supply passage between the main tank and the print heads in the ink jet printer, the amount of the ink supply is different among the respective ink jet printers. For example, in a case where plural ink jet printers are laid horizontally, an ink jet printer located farthest from the main tank has the longest ink flowing passage. Therefore, in its ink jet printer, an ink supply time becomes longest. On the contrary, since an ink jet printer located nearest to the main tank has the shortest ink flowing passage, the ink supply time becomes shortest.
In a case where the main tank is arranged at the lowest position and plural ink jet printers are laid in the vertical direction, an ink jet printer located at the top has the longest ink flowing passage and also the largest pressure loss due to the head difference, so that the ink supply time becomes longest. On the contrary, an ink jet printer located at the lowest position has the shortest ink flowing passage and also the smallest pressure loss due to the head difference, so that the ink supply time becomes shortest.
Further, since the amount of ink consumption amount is large in the image printing by the plural ink jet printers, the amount management is important. Conventionally, such amount is managed every each ink jet printer.